After computer motherboards are changed from the AT specification to the ATX specification, the architecture of a power supply device for supplying electric power is also changed, particularly the output of the power supply device is divided into a primary output power and a stationary power supplied by a primary power system and a stationary power system in the power supply device respectively, wherein the stationary power system is turned on after an input power is obtained by the input power source, the input power is converted into the stationary power to normally provide a sleep mode for the stationary power to achieve the remote ON function required by the ATX specification. If a user presses an ON button or turns on the computer by a remote control, the stationary power will be supplied as an electric power for turning on the primary power system, and thus the primary power system will generate a primary output power for the operations of an electronic device. In FIG. 1, a conventional power supply device includes a filter-rectifier unit 1, a power factor correction unit 2, a primary power system 3 and a stationary power system 4. The filter-rectifier unit 1 is provided for filtering and rectifying an obtained input power 91, boosting the voltage by the power factor correction unit 2 and adjusting the phase. The primary power system 3 further includes a primary pulse control unit 31 and a primary power conversion unit 32. The primary pulse control unit 31 cannot operate without a bias voltage power. In other words, the primary power system 3 cannot output power normally. On the other hand, the stationary power system 4 includes a stationary pulse control unit 41 and a stationary power conversion unit 42, and the stationary pulse control unit 41 obtains a reference frequency signal 95 and the input power 91 to drive the stationary power conversion unit 42 according to the reference frequency to convert and generate a stationary power 93 to be outputted to an output terminal 97. The stationary power system 4 generates a first standby signal to a power management unit 5. After a remote ON/OFF signal 94 triggers the power management unit 5, the power management unit 5 outputs the bias voltage power to turn on the primary pulse control unit 31, and the primary power system 3 starts working and provides a primary output power 92 to another output terminal 97. However, after the primary power system 3 is turned on, the stationary power system 4 remains working, and a pulse control and a transformer circuit used by the primary power system 3 and the stationary power system 4 for converting electric power are independent devices. Therefore, the primary power system 3 and the stationary power system 4 of the power supply device will have a power loss, and thus causing adverse effects of poor input/output conversion efficiency and excessive waste heat. The aforementioned two adverse effects will incur a higher design cost and a shorter life of the power supply device. If the stationary power system 4 is used normally for the power supply device as usual, the power loss issue of the conventional primary power system 3 and stationary power system 4 definitely requires improvements.